A friend of mine with the beginnings of astigmatism brought up that he was looking for a scope for ranges out to about 500 yards he could mount on his AR that would work for him. The Vortex Crossfire II with the Vbrite reticle he has is giving him a hard time. Besides astigmatism specific glasses or contacts, which I just learned existed last night and will bring up when I see him again, what scope options are available?